


On the Straight and Narrow

by doctor__idiot



Series: SPN Kink Bingo 2017 [12]
Category: Supernatural
Genre: Bottom Dean, First Time, Incest Kink, M/M, Mentions of Underage, Rough Sex, Season/Series 01, Supernatural Kink Bingo 2017, Top Sam, slight size kink
Language: English
Status: Completed
Published: 2017-08-27
Updated: 2017-08-27
Packaged: 2018-12-20 15:07:01
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 979
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11923461
Author URL: https://archiveofourown.org/users/doctor__idiot/pseuds/doctor__idiot
Summary: Dean never thought that this is the way it would go down.





	On the Straight and Narrow

**Author's Note:**

> Written for the [SPN Kink Bingo](http://spnkinkbingo.tumblr.com) square "Incest Kink". I just have such a thing for toppy Sammy, sue me.

Dean never thought that this is the way it would go down.

Back when Sam was still Sammy, was still basically a baby to Dean but growing into himself, was nothing but bones and knobby joints but all smile, Dean knew it’d be impossible to keep them on the straight and narrow.

And, ha, _straight_ , wasn’t that the funniest pun. Only, it’s not so funny when it’s your little brother you’re lusting after before he’s even had the chance to figure out for himself what he wants.

It hurt more than it should, more than Dean can say, that what he wanted never seemed to be Dean.

They sparred, tussled, rough and tumble, and Dean never wanted to think about what it meant that it got easier once Sam’s lingering baby fat disappeared and puberty left him with a deeper voice and only an inch short of Dean’s own height.

Now Dean knows he was fooling himself. Because as much as it got easier, it got so _so_ much worse when Sam turned eighteen, technically legal, just not legal enough, not for Dean. So maybe Stanford was a godsend.

Dean lived in cotton, senses dulled by too much alcohol and too many bruises.

One nightly disturbance and Sam stands before him at twenty-two, well over six feet tall and disgruntled, and want slams into Dean sudden enough to knock the breath right out of him. It isn’t the same desire as before, not the teenager crush born from care and familiarity, it’s something entirely different. Something Dean hasn’t experienced so far.

He wants things he’s never wanted before.

Sam’s shoulders are wider than his, waist trim and hips narrow, legs too long for Dean to keep up with, and against his better judgement Dean wants to keep his brother perpetually angry and scowling because Sam is _vicious_.

Deliciously brutal, nearly breaking Dean’s wrists as he twists him against the motel room wall and bites his skin, and Dean makes a sound he’s never made before. His body is betraying him and he doesn’t fully understand until Sam’s hefts him up against his waist like he weighs nothing and hisses, “Been waiting for this, big brother.”

Hiccups, sobs, Dean fists his hand in Sam’s shaggy hair, too reminiscent of his long-gone younger self, and Sam _snarls_. Dean tastes blood, doesn’t care. Opens up with a greedy moan.

It shakes all the way through him, Sam’s fingers digging into sweat-slippery skin, rock-hard cock trapped against Sam’s stomach. Muscles bulge under Dean’s palms where he holds onto his brother’s biceps and it’s too much, his voice breaking, “ _Sammy_.”

Sam hums, licks into his mouth, gentler now but never giving up control. “Haven’t called me that in ages,” he says as Dean shivers, “Not since you used to look at me. Noticed you looking. Jailbait, Dean, but you liked it, didn’t you?”

It sounds almost like a reprimand and Dean groans. “Sorry, so sorry, _fuck_ –“

Sam tugs him away from the wall, to the bed, husks, “I liked you looking.”

Dean whimpers, can’t help it. He’s half-naked, feeling entirely exposed, and Sam isn’t naked _enough_ , but Sam’s already grabbed his hands again, pushing the up _up_ over Dean’s head until he squirms under the bigger body of his little brother and _Jesus_ –

“Say it again, Dean.”

Hoarse whisper, “Sammy.”

Sam’s tongue is in his navel, the crease of his thigh, teeth on his hipbone, and Dean tosses, knees on either side of Sam’s shoulders. Elbows knock them to the side, opening him up more, and Dean squeezes his eyes shut. He’s going insane, going insane, because that’s his baby brother’s mouth on his cock, his baby brother’s fingers in his ass, and then – _oh._

Sam’s hands smooth down his sides as Dean trembles. He’s clutching, keening, “Sam, _Sammy_ , fuck!”

“Tell me how it feels,” Sam urges, “Tell me how it feels to have your little brother’s cock fill you up. So desperate for it, aren’t you, big brother?”

Dean bites his fist against a scream, the burn and the spark of all that meat inside of him rubbing his prostrate and making him lose his mind.

“Oh _god,_ ” he gasps when Sam tilts his hips, forcing Dean to take him deeper, and Dean arches his back, too much, too much and not enough. Never gonna be enough ever again unless Sam–

“Come on,” Sam whispers, his breath on Dean’s skin, slightest brush of mouths, “C’mon, baby, tell me.”

“So good, baby boy, _Christ_ , I need–“ Dean’s breath stutters when Sam slams into him hard, fingers pressing purple into Dean’s hips, “Need to come, Sammy, _please._ ”

Sam’s damp hair tickles the side of his face. “On my dick, Dean. Just like this.”

He picks up his pace and this time Dean doesn’t bother trying to muffle his shout, blunt nails biting crescent shapes into Sam’s shoulders. He’s aching, wants all the marks, bruises. Welcomes them.

Sam kisses the corner of his mouth, tongue flicking against Dean’s bottom lip. “You’re mine, big brother. Always gonna be mine now.”

Dean gasps, no hesitation. “Always been yours, baby. Never anyone else’s.”

The bite Sam delivers to the hollow of Dean’s throat almost hurts, body jerking, but Sam’s clever tongue soothes the pain, hips pumping, opening Dean up in more ways than one, and he crashes his mouth down on Dean’s when he comes, almost at the same time as Dean does.

It’s too dark to see the flush of their skin but Dean can tell the glint in Sam’s amber eyes even in the dim moonlight and he holds him inside until they’re both too sensitive, too exhausted.

“Sam?” he asks into the chilly darkness later, skin tender and voice used, and Sam snakes his arm around Dean’s chest from behind. Soft lips find the spot behind his ear. “Yeah,” Sam says, just as rough, “I know.”


End file.
